November 5, 2012

New Device Could Use Heartbeats To Power Pacemakers

The artificial pacemaker, a device that helps regulate the human heart through electrical impulses, has been widely used in cardiac patients for decades. However, these patients must undergo regular procedures to replace batteries when they wear out, raising the risk for infections and other complications. But now, researchers believe they have a new form of energy that can power pacemakers well beyond the life of conventional batteries: the heart itself.

Scientists from the University of Michigan at Ann Arbor have developed a prototype pacemaker that actually runs on the electrical charge generated from the motion of the heart beating, called piezoelectricity.

This is a promising technical solution for pacemakers, because they require only small amounts of energy to operate, according to Amin Karami, PhD, of the Department of Aerospace Engineering at UMich, lead author of the study.

Initial tests suggest the device could produce 10 times the amount of energy needed, and patients could power their own pacemakers, eliminating the need for battery replacement operations.

The British Heart Foundation said, however, that clinical trials would be needed to prove the device´s effectiveness and to ensure its safety.

The research team suggest piezoelectricity could also power other implantable cardiac devices such as defibrillators, which also require only minimal energy needs, said Karami.

“Many of the patients are children who live with pacemakers for many years,” he said. “You can imagine how many operations they are spared if this new technology is implemented.”

The researchers actually came across the medical breakthrough by accident--they were looking to design a light unmanned aircraft that could be powered by the vibrations of its own wings. Through this research, the team realized that the properties of power-generating piezoelectric materials could potentially be applied to powering pacemakers.

Using piezoelectricity to power pacemakers could save patients from countless operations, noted Karami.

To be sure, Karami and his colleagues measured heartbeat-induced vibrations in the chest. They then used a ℠shaker´ to reproduce the vibrations in the lab setting and connected it to a prototype cardiac energy harvester they had developed. Measurements of the device´s performance, based on a wide range of simulated heartbeats, showed the energy harvester generated more than enough power required by modern pacemakers.

Karami said the device they used in the experiments is about half the size of batteries now used in pacemakers and also includes a self-powering back-up capacitor.

Typical pacemakers can be powered by two types of energy: linear and nonlinear. Linear harvesters only work well at specific heart rates, so if the heart´s rate changes it may prevent the linear harvester from working properly.

But nonlinear harvesters--the type used in the study--use magnets to enhance power production, making them less sensitive to heart rate changes. Using the nonlinear harvester, the team was able to generate enough power, even when changing heartbeats from 20 to 600 beats per minute.

Another plus with nonlinear harvesters: devices such as cellphones and microwave ovens do not affect them, noted Karami.

“What we have proven is that under optimal conditions, this concept is working,” he told Mail Online.

About 100,000 people each year in the US who have heart rhythm disturbances get a pacemaker. These devices sell for about $5,000, which does not include the cost of surgery. And further care--operations that need to be done to replace the batteries, about once every seven years--adds to this cost.